This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Kathleen Schell Accuracy of Non-invasive Blood Pressure Monitoring Accurate blood pressure (BP) measurement is integral to appropriate healthcare. Error in measurement may lead to under- or over-treatment. Although the mercury sphygmomanometer is considered the gold standard for BP measurement, automated oscillometric devices have become more common for obtaining routine and emergent vital signs of clients in healthcare settings. This automatic device is more convenient and avoids errors that arise from auscultation. However, other aspects of BP measurement such as limb placement in relation to the client's heart, cuff size, and cuff placement may also produce error. When individuals'upper arms are not accessible and/or when the BP cuffs do not fit upper arms, alternate sites have been used, including the forearm and the ankle/calf. The National Heart, Lung, and Blood Institute and other experts in the USA and Europe have called for validation of BP measurement techniques and equipment. The overall goal of my research is to investigate the accuracy of multiple methods of non-invasive BP monitoring across the lifespan so that clinical decision making will be informed by reliable measurements. This work has lead to analysis of anatomical determinants of BP differences between the sites with the goal of influencing the design of automatic blood pressure devices. The purposes of the two completed studies were: Study 1 - To compare oscillometric upper arm and calf blood pressures in children ages 1 to 8 years, admitted to a Pediatric Intensive Care Unit;and Study 2 - To compare oscillometric upper arm and forearm blood pressures in critically ill adults.